… has not been to express my own perspective on what should be considered offside, but rather to describe the training I received. I was specifically taught that an affirmative repositioning by the GK, to cover the possibility of a pass to the player in OS position, was NOT alone sufficient to trigger a determination of active involvement in the play.

Were I in charge of writing the Laws, or of guiding their implementation, I would find that affirmative repositioning, or the GK’s maintenance of a suboptimal position for the same purpose, to be sufficient for an OS call, as I suspect you would. I’ve watched the play now about a dozen times, and I’m not sure that standard is met here.

Where you and I part company is with your point about the defender on the right who hypothetically slows because of a conviction that the player in OS position will play the ball before the player whom the defender is marking. I can’t imagine why we would want an OS rule that protects the defender from the consequences of that particular decision.

Thanks for explaining your view. I found it interesting and thought-provoking.